Many individuals are affected by eczema or inflammation of the skin. A topic dermatitis is the most severe and chronic form of eczema, although there are several other skin conditions that are eczemas including seborrheic dermatitis, irritant contact dermatitis, and allergic contact dermatitis. Skin inflammations may be triggered by any number of factors. For example, irritant contact (such as by solvents, chemicals, detergents, etc.) may trigger eczema. Eczema may also be triggered by allergens, for example by dermal exposure to plant species such as poison ivy, poison oak and poison sumac. Individuals with severe eczema such as a topic dermatitis are often prone to secondary skin infections such as by Staphylococcus bacteria or Herpes virus.
It is known in the art to treat inflammatory and pruritic manifestations of dermatitis syndromes topically with corticosteroids. The mechanism of anti-inflammatory actions of topical corticosteroids has not been completely elucidated. However, it is thought that corticosteroids act by inducing phospholipase A.sub.2 inhibitory proteins called lipocortins. Lipocortins may control synthesis of potent mediators of inflammation such as prostaglandins and leukotrienes.
Heretofore, corticosteroid treatments for dermatitis have been topical applications in the form of creams gels, or lotions. These medicamentous vehicles tend to leave a greasy layer on the treated area which can be unpleasant to the recipient. Additionally, the task of preparing the appropriate suspension of active ingredients in a cream, lotion, or gel form can be laborious. Thus, the prior compositions of active medicaments, dispersed in their related delivery media, do not provide an ideal solution for treating dermal inflammation and irritation.
More importantly, corticosteroid treatments for dermatitis have traditionally incorporated higher concentrations of steroid, typically 0.1 percent by weight or higher, to provide beneficial effects. For example, U.S. Pat. No. 4,343,798 teaches use of corticosteroids in combination with C.sub.5 -C.sub.12 fatty acids for topical treatment of inflammatory skin conditions. Typical concentrations of corticosteroid taught in the '798 patent include 0.5 percent by weight beclomethasone dipropionate, 0.1 percent by weight hydrocortisone butyrate, 1 percent by weight hydrocortisone with urea, and 0.1 percent by weight triamcinolone acetonide. Similarly, U.S. Pat. No. 4,107,161 teaches use of a triamcinolone isomer at concentrations ranging from 0.1 percent to 0.5 percent by weight.
There are significant disadvantages to prior compositions which utilize corticosteroids in higher concentrations. Systemic absorption of topical corticosteroids may produce a reversible hypothalamic-pituitary-adrenal (HPA) axis suppression with the potential for glucocorticosteroid insufficiency after withdrawal of treatment. Manifestations of Cushing's syndrome, hyperglycemia, and glucosuria may also occur in some patients by systemic absorption of topical corticosteroids during treatment. Pediatric patients, patients receiving treatment with superpotent corticosteroids, patients applying topical steroids over a large skin surface area, and patients applying corticosteroids to areas under occlusion are at particular risk. Due to potentially harmful side effects, current formulations employing corticosteroids for topical treatment of skin inflammation are often limited in terms of the size of the skin area which may be treated and the length of time over which treatment may occur.
Often, however, eczemas (such as allergic contact dermatitis) which are of uncertain origin and chronic in nature manifest in patients, necessitating longer-term treatments and treatments over large skin areas. There is thus need in the art for a corticosteroid treatment for chronic dermatitis which incorporates lower concentrations of corticosteroid and is therefore suitable for longer periods of treatment. There is also need for such a corticosteroid treatment which may be conveniently applied over large skin surface areas without the disadvantages associated with cream or lotion carriers. One such means for avoiding cream or lotion formulations is a dip treatment. However, dipping is unsuitable for larger patients such as humans or large animals due to difficulties in application and the large quantities of medicament required. In response to the need in the art, the applicant has developed a new and improved spray formulation that successfully treats skin conditions such as chronic, non-responsive allergic dermatitis which incorporates reduced concentrations of corticosteroid.